The jaw-dropping 'Alien: Romulus' ending sets it apart from other blockbusters. Here's what happens.

• "Alien: Romulus" is set on a derelict space station where a group of scavengers face the Xenomorphs.
• The final act of the film cranks up the horror with a stunning twist.

Warning: Major spoilers ahead for "Alien: Romulus."

"Alien: Romulus" is set in between the events of 1979's "Alien" and 1986's "Aliens" when a group of scavengers from the Jackson's Star mining colony raid a derelict space station, looking for a way to escape their bleak existence.

Predictably, the group sticks its nose where it doesn't belong, and a young woman named Navarro (Aileen Wu) ends up on the wrong side of a Facehugger. This leads to a bloodthirsty fight for survival as the Xenomorphs overrun the station.

"Alien: Romulus" could easily have replicated the other films in the franchise and simply focused on the terrifying nature of the Xenomorph.

But "Evil Dead" director Fede Alvarez pushes things further in the second half of the film when he ties it to the 2012 prequel "Prometheus," and cranks up the body horror with a stunningly gruesome twist.

Here's the ending, explained.

Weyland-Yutani experimented with the black goo from "Prometheus."

Rain (Cailee Spaeny) travels with a crew, including her adopted android brother, Andy (David Jonsson), to the "Renaissance" station, which is divided into two sections. They find themselves in the section called "Remus," where all the Facehuggers are kept in cryo-storage.

When the crew's ship, the Corbelan IV, gets accidentally knocked over to the other side of the station, called "Romulus," Rain and Tyler (Archie Renaux) have to fight their way over to the second half.

They discover that Weyland-Yutani, the nefarious company that owns the station and the colony, has synthesized a black serum from the Xenomorphs and the Facehuggers.

It's the same black substance that appears in Ridley Scott's "Prometheus." It drastically alters the DNA of a living organism to evolve it into something more monstrous. Weyland-Yutani wants to use the goo to create a workforce that doesn't get sick when they terraform planets or mine alien worlds for resources.

But when they continue to make their way to the ship, Kay (Isabela Merced), who is pregnant, gets taken by the Xenomorph. She narrowly survives the ordeal, albeit with some injuries, and she injects the goo into her neck in an attempt to save her unborn child.

Fast-forward 20 minutes, and Kay endures a hideous birth because the serum has accelerated her baby's growth — and also genetically altered the fetus. She painfully delivers an alien egg, which contains a Xenomorph/human hybrid inside.

The "Offspring" feeds on Kay.

The creature — called the "Offspring" in the credits — almost immediately grows to a towering size and starts feeding on Kay because her body secretes more of the gooey substance seen in the Romulus lab.

It's a horrific twist on the Renaissance-era painting seen on the wall of the station earlier in the film, which depicts a newborn baby suckling on its mother's corpse.

Kay's Xenomorph/human baby also looks notably similar to the 10-foot-tall Engineers who appeared in "Prometheus" and were essentially responsible for creating mankind.

Rain slips into a spacesuit while the Offspring suckles on its now-dead mother. When the Offspring eventually chases Rain, she detaches the ship's cargo container into the asteroid field below so the monstrous being gets bombarded by the debris.

Like any good horror film though, the Offspring manages to rear its ugly head into the camera for one last jumpscare before it gets seemingly annihilated in space.

The whole sequence, filled with practical effects, feels like an instant adrenaline rush that sets it apart from many other blockbusters, which often deliver predictable fight scenes filled with dull CGI.

Rain and Andy survive and head to Yvaga III.

Rain and her adopted android sibling are the only surviving members of the crew after their ordeal on the Renaissance station, and Rain puts them both into stasis pods as they set the ship on a course to Yvaga III — a supposedly peaceful planet.

In a narration that mirrors Ripley's (Sigourney Weaver) at the end of the original "Alien" movie, Rain notes that she's not sure if the ship will make it to Yvaga III, but she's hopeful about the future.

This is a considerable shift in her demeanor considering how worried she was about life at the start of the story.

"Alien: Romulus" has no post-credits scenes, but the ending leaves plenty of room for a sequel.

Audiences don't have to stick around while the credits roll, as there isn't an extra scene waiting at the end. (Although it's always worth noting all the people who worked hard on the film!)

But the absence of a post-credits scene doesn't mean that a sequel isn't possible.

It would be very easy for 20th Century Studios to find a way to bring Spaeny and Jonsson back for a follow-up mvoie. As fans have seen in previous "Alien" films, all it takes is for one Facehugger to have snuck onboard the ship, and this could all start again.

Alternatively, the story could pick up with Weyland-Yutani searching for the remains of the Xenomorph/human hybrid, since the company is so concerned with creating the perfect organism.

The film also specifically points out that androids are not welcome on Yvaga III, which could be a problem for Rain and Andy if they make it to their destination.